This disclosure relates to a method for closed-loop control of the surface temperature of a glow plug.
In known methods, the electrical resistance of the glow plug is used as a control variable. Here, the electrical resistance is calculated from continuously measured values of the heating current and of the electrical voltage and is compared with a target value, which is established from a predefined target temperature by means of a temperature/resistance characteristic curve.
The quality of the temperature control achieved in this way with known methods is poor, however. This is true in particular for ceramic glow plugs which show large variations of the cold resistance as a result of the manufacturing process.